Caissons Are Bridge to Revolutionary War

For more than two centuries, the waters of Lake Champlain have hidden the remains of a marvel of 18th century engineering -- a bridge built by 2,500 sick and hungry Continental soldiers.

Now a piece of that bridge sits in the preservation laboratory at the Lake Champlain Maritime Museum, destined to give visitors a portal into revolutionary times.

“When you look at what they wanted to do, it connects you right to the American Revolution,” said Art Cohn, the museum’s executive director.

Historians say the bridge was constructed in March and April of 1777. Thousands of huge pine logs were skidded onto the ice and notched together; weighed down with rocks, these caissons sunk to the lake bottom through holes the soldiers cut in the ice.

By spring, 22 caissons, some up to 50 feet tall, reached the lake’s surface. They were joined by a 16-foot-wide deck that linked Ft. Ticonderoga in New York and Mount Independence in Vermont.

The American troops were soon forced to use the bridge they had built. In July 1777, they fled the British army that was bearing down on Ft. Ticonderoga.

The British occupied the fort and later destroyed the bridge. But many of those same colonial troops who fled Ticonderoga played a role three months later in defeating the British in the Battle of Saratoga, one of the pivotal battles of the Revolutionary War.

If the part of the bridge above the water was destroyed, the part under the surface was not. The caissons were set so deep that they did not interfere with boats on the lake; the bridge was largely forgotten until 1983, when divers discovered the caissons, still largely intact, laid out in an arc between the two shores.

Cohn and others began to study the bridge more intensely in 1992, mapping the locations of the caissons, and recovered thousands of Revolutionary War artifacts believed to have been dumped in the lake when the British abandoned the fortifications in late 1777. Some of those artifacts are on display at the Mount Independence Visitor Center in Orwell.

Then last year, a 26-foot beam estimated to weigh between 1,500 and 1,800 pounds surfaced and was pulled to shore near Ft. Ticonderoga. It sat there until December, when the ground was frozen enough so that a truck could be driven down to the water’s edge and the beam could be retrieved.

It was taken to the Maritime Museum, to be dried out and prepared for public display.

The cold lake water helped preserve the timber, believed to be dense white pine.

“The wood was never completely waterlogged,” said Chris Sabic, director of conservation.

“The conservation is going to be very passive,” he said. “We’re not trying to impregnate it with chemicals. We are really just letting it dry out as slowly as possible in a controlled environment.”

That control comes from simply wrapping a plastic tarp around the beam for part of the day.

Once preservation of the timber is complete, it will be displayed at the Maritime Museum. Cohn said it would be returned to the museum at Ft. Ticonderoga after a new visitor center is finished.

The simple conservation technique is a marked contrast from other wooden Lake Champlain artifacts that have required months or years of expensive preservation.

For example, it took years to preserve an anchor from a British warship from the War of 1812 that was pulled from the lake near Plattsburgh, N.Y. In that case, the anchor was dried by soaking it in alcohol. Then it was soaked in a solution that contained pine rosin.